The invention relates to compositions and methods for delivering labeled compositions, including compositions labeled with radioisotopes such as yttrium-90 (Y-90) and palladium-103 (Pd-103), for a variety of medical and research purposes including internal radiation therapy and embolization with or without the incorporation of radioisotopes. For example, internal radiation therapy is successfully used in treating autoimmune disorders such as rheumatoid arthritis and a variety of concerns such as solid tumors associated with liver cancer, prostate cancer, breast cancer and pancreatic cancer.
Treatment of arthritis, to date, includes medical therapy, surgery and total joint replacement. However, all of these procedures have limitations. For example, medical therapy generally targets inflammatory arthritis through a host of chemical agents with varying degrees of effectiveness, whereas surgical synovectomy is effective treatment, but generally last only three to five years before the synovium (inflammed joint tissue) regenerates. Clinical trial data indicates that radiation synovectomy of rheumatoid arthritis is comparable to surgical synovectomy. In particular, radiation synovectomy using e.g. yttrium-90 is effective in suppressing the inflamed synovium and relieving pain. In a published survey conducted from 1991-1993, at least 13,450 different joint injections in 8,578 patients were administered in Europe, and of these injections, Y-90 colloids were used in almost 90% of the medical centers responding to the survey. Rheumatoid arthritis was found to be the most prevalent disease in patients treated (76%), and knee and finger joints were the most frequently treated joints, 46% and 20% respectively. However, due to the lack of an appropriate delivery vehicle, confining the radioisotopes to the joint cavity was not achieved and unacceptable widespread dissemination of the radioisotope throughout the body occurred.
Radiotherapy has also found wide applicability in the treatment of various tumors. For example, there are many types of solid tumors that are resistant to treatment methods other than radiotherapy, such as solid tumors associated with liver, prostate, breast and pancreatic cancers. One effective solid tumor treatment includes internal radiotherapy by means of intra-arterially injected microspheres. As early as the 1960s, inoperable primary pancreatic and liver cancer were treated by the intra-arterial administration of Y-90 ceramic microspheres (supplied by 3M Company).
One example of a microsphere using radioactive yttrium is set forth in Day et al. (U.S. Pat. No. 5,011,677) discloses radioactive glass microspheres wherein the microspheres are completely non-radioactive until irradiated for use in therapy, and becomes radioactive after irradiation in a suitable neutron beam reactor. While Day et al.'s microspheres provide a therapeutically useful dose of radiation and purport to prevent leakage, absent surgical removal, the microspheres remain entrapped in the patient's body. Similarly, Gray (U.S. Pat. No. 6,537,518) discloses radioactive microspheres made of ceramic. However, both lack the ability to offer traceability or other diagnostic function during or after administration of the microspheres. Furthermore, Y-90 microspheres, described by both Gray and Day are not prepared by directly incorporating Y-90 during the formation of the microspheres. Instead, microspheres are prepared using non-radioactive material first. Then, the Y-90 is either attached (e.g., coating) to pre-made microspheres (Gray), or is created within pre-made microspheres by means of neutron irradiation (e.g., Day, Gray).
Thus, to date, the art has attempted to strike a balance between the chemical durability and non-leakage of non-resorbable implants, and the promise of bioresorbable implants that do not require surgical removal. Additionally, there is a need in the art to provide effective imaging, diagnosis and treatment without the interference and health hazards associated with using conductive implants (e.g. gold, silver or platinum wire) when using Magnetic Resonance Spectroscopy (MRS) or Magnetic Resonance Imaging (MRI). There still exists a need in the art for an implant which permits localized delivery of radioisotopes for radiotherapy, without leakage, but which is resorbable, thereby dispensing with the need for choosing between the undesirable choices of either subsequent surgical removal of the implant or leaving the implant in the patient.